JP2005509992A - Stamper, master plate, support structure manufacturing method and use of the stamper - Google Patents

Abstract

  A method of manufacturing a stamper for use in manufacturing a small form factor (SFF) optical data storage medium is provided. The conventional master plate (2) is a spiral or concentric information track having a relief structure with the center of each area (3a to 3h) located outside the rotation axis (9) of the master plate (2). Provided with a series of areas having (3a-3h). This is done by using a conventional master recorder and a separate master plate support structure (1) that does not require the complex movement of the master recorder write head. The master plate (2) obtained in this way is used to produce a stamper containing a negative replica of the surface of the master plate (2).

Description

  The present invention relates to a method of manufacturing a stamper for use in the manufacture of a storage medium for optical data, in such a method, a substrate having a rotating shaft and a recording layer sensitive to a radiation beam provided on the substrate. The master plate is exposed to a modulated radiation beam, and in such a method, a series of areas with helical or concentric information tracks having a relief structure are located outside the rotation axis of the master plate. Formed in the recording layer with the center of each area followed by a stamper, and also in this method the relief structure of the information track of the master plate is copied, formed on the master plate and separated from the master plate The

  The invention further relates to a master plate produced by the method described above.

  The invention further relates to a support structure for use in the aforementioned method.

  The invention further relates to the use of a stamper produced by the method described above.

  Methods of the type mentioned in the above technical field are known (for example, see Patent Document 1).

  For example, optically readable optical data storage media, such as digital information, are typically reflective and non-reflective, or at least less reflective areas formed of a synthetic plastic material relief on the substrate of the optical information medium. It is made up of “pits” and is provided with a spiral track starting at a small distance from the carrier edge or carrier center. The spiral track stops at a small distance from the center of the optical information medium or adjacent to the edge of the optical information medium. This track can be scanned by means of a radiation beam, such as a laser beam, for example, to provide a series of digitized pulses that can be converted into data such as images, sounds, or text. Optical data storage media are generally generated in large quantities by an injection molding process. In this step, a stamper having a negative relief structure, which is inscribed on the substrate of the optical disk medium, is located in the mold of the injection molding apparatus. It is very important that the disk-shaped stamper has the longest useful life possible and that the injection molding process has the shortest possible cycle. According to U.S. Pat. No. 6,057,051, a method with a fairly short cycle is achieved by forming on the master plate four spiral information tracks with the center of each spiral track located outside the center of the master disk. Furthermore, it is described by generating a disk-shaped negative replica of nickel called a stamper from the master plate. In this manner, the maximum diameter of the resulting optical storage medium is limited, while the cycle of the injection molding process for each optical storage medium is reduced by a factor of about four. However, such media have a high information density per area because conventional optical information can use edge and center areas that are usually unsuitable for use because of the need for poor reflective properties and relatively large central holes. May be included. This is because the center and edge portions of the information medium have the same homogeneity with respect to the optical properties due to the position away from the center of the master plate. Indeed, a series of helical information tracks can be provided between the edge and the center of a conventional optical information medium to provide an annular area with the desired reflective properties. Providing a single helical information track on a circular master plate from the edge of the plate to the center or vice versa is relatively simple mechanically. The master plate can be rotated and the “write head” for providing the information track can be driven at a uniform speed according to a radial line having the center of the master plate.

However, the spiral on the standard master plate when the center of each area is outside the center of the master plate, as the spiral movement no longer separates or can no longer be divided onto the “write head” of the master plate and master recorder. Providing a series of areas with a number of information tracks is a problem with known methods that are very complex. The “write head” itself should be driven according to a complex spiral movement. This movement is not possible with a standard master recorder. In order to overcome this problem, the known method according to US Pat. No. 6,057,096 is based on four individual discs of the size of the ultimate optical information medium fitted in a circular holder having a recess for receiving four individual discs. A special master plate that can be formed as a composite part is used. Each of these individual discs should be created individually using conventional techniques. It is clear that the problem is to use a master plate with many parts. First, standard master plates cannot be used. Second, positioning four individual discs in the recesses creates slits or grooves that may have undesirable effects such as inhomogeneous layer thickness during the stamper formation process. Thirdly, such special master plates are very expensive.
European Patent Application No. 0355925A1

  The object of the present invention is therefore an introductory provision in which a standard master plate is provided with a series of areas with spiral or concentric information tracks as described in the preface in a simple manner with a standard master recorder. It is to provide a method of the type described in.

According to the present invention, the above-mentioned object is as follows: a) In the step of exposing the recording layer to the modulated radiation beam, the master plate is fixed eccentrically with respect to the axis of rotation of the support structure; The axis of rotation is substantially perpendicular to the substrate surface of the master plate, and the support structure with the added master plate is rotated along the axis of rotation of the support structure;
b) the first area of the series of areas is exposed to a radiation beam forming an information track, while the center of the first area coincides with the axis of rotation of the support structure;
c) The master plate is ejected from the support structure and moved relative to the support structure until the center of the later area coincides with the axis of rotation of the support structure and is fixed again with respect to the support structure;
d) the latter area is exposed to a radiation beam forming an information track;
e) Steps c) and d) are repeated until all areas of the series of areas are exposed to the radiation beam,
Is achieved by a method characterized by

  By using the method described above, a conventional standard master plate may be provided with a number of areas with information tracks as described in the introduction using a conventional master recorder. By eccentrically placing a conventional master plate on the support structure, a number of areas may be subsequently exposed. Later area exposure is performed in the same manner on a standard master plate and no modification of a conventional master recorder is required. Such an area corresponds to the information area of the final optical medium. Note that the term master plate does not include the most commonly used circular master disk, but includes other shaped master plates. Currently, small optical storage media of interest are growing. Such small optical media in the disk embodiment may be referred to as a Small Form Factor (SFF) optical disk. These discs are better as audio and communication devices, such as digital camcorders, digital still cameras, digital audio players and mobile phones, as storage media for imaging and the size of the storage media device is clearly an important attribute. It is becoming important. The method according to the invention is very suitable in providing a master plate for producing stampers in the production of SFF optical discs.

  In a preferred embodiment of the present invention, in step c), the master plate rotates about the axis of rotation of the master plate, and the axis of rotation of the master plate is in a fixed position on the support structure. This has the advantage that during rotation of the master plate a standard master plate center chuck may be used as a centering means to the receiving holder of the support structure. After rotation around this chuck, the master plate may be fixed relative to the support structure, for example, by well-known vacuum techniques.

  In another preferred embodiment of the above method, the master plate is substantially equal to 360 / n degrees, rotates n-1 and n is an integer greater than one. In this approach, a rotationally symmetric set of the above areas is generated on the master plate and later stamper. This has the advantage of further facilitating the processing of injection molded substrates with stampers and a number of SFF optical disks that still have to be cut. Typically, a mask is used to prevent metal deposition, typically about 1 mm, on the outer edge of the substrate during deposition of the metallic reflective layer on an injection molded substrate such as sputtering. The purpose is to prevent corrosion of the metal adjacent to the outer edge. This is because if the outer edge of the substrate does not have metal, the protective layer applied after deposition of the metal layer contacts the substrate, thereby completely sealing the metal layer from the external environment. In the case of multiple SFF disks per substrate, masking should still be made at the “outer end” of the SFF disk that does not cut inside the large substrate. It is relatively simple to design a sputtering masking tool for masking the “outer edge” of SFF disks, if the tangents and radiation positions of those SFF disks are accurately defined. This is accurately achieved when using the method of this embodiment described above. Further, for example, the cutting tool may be used when the first SFF optical disk is cut after alignment, followed by cutting the subsequent substrate while the substrate is rotated n-1 at 360 / n degrees. .

  Particularly suitable is the use of a master plate having a diameter of 150-170 mm and an area for recording helical or concentric information tracks shorter than 40 mm. A standard master plate has a diameter of 160 mm, for example provided with the above-mentioned area having a diameter of 30 mm. A diameter shorter than 40 mm would be a suitable size for an SFF optical disc. For a 160 mm master plate, if n is one of 8, 9, and 10, it is advantageous that the rotation axis of the master plate on the support structure has 30 to 55 mm, for example 43 mm, to the rotation axis of the support structure. In this manner, an optimal maximum number of areas can be provided for the annular zone on the master plate.

  A preferred embodiment of a support structure suitable for use in the above-described method is that the support structure has at least one counterweight to balance the mass of the added master plate, so that the support structure and the added master The center of gravity of the plate assembly is substantially coincident with the axis of rotation of the support structure. It is advantageous to have a balanced assembly of support structures and an added master plate, since the support structure is rotated by the master recorder at a rotational speed much faster than for example 300 RPM. By equilibrium is meant either statically balanced or statically / dynamically balanced. The balanced assembly prevents unwanted vibrations and prevents forces during recording that may cause written track deviations.

  In another preferred embodiment of the support structure, the counterweight is movable with respect to the axis of rotation of the support structure. This has the advantage that a slight deviation in the mass of the master plate can be compensated by a slight movement of the counterweight, and thus the center of gravity of the assembly can be adjusted to a desired position, for example the axis of rotation of the support structure.

  In yet another embodiment of the support structure, the counterweight is removable from the support structure. If a new master plate with a mass that deviates significantly from the standard master plate is introduced, it may be necessary to replace the counterweight with another counterweight having a heavy or light mass. Simply moving the counterweight may not be sufficient to compensate for the large deviations described above.

  An embodiment of a support structure and master plate assembly for carrying out the method according to the invention will be described with reference to the accompanying drawings. It should be noted that the drawings are schematic.

  1 and 2, an assembly of a support structure 1 and a master plate 2 for performing a method of manufacturing a stamper for use in the manufacture of optical data storage media is shown. The master plate 2 includes a substrate 2a made of glass and a recording layer 2b that is highly sensitive to a radiation beam provided on the substrate. The recording layer 2b is exposed to the modulated radiation beam 10. A series of areas 3a to 3h including a spiral or concentric information track having a relief structure is formed in the recording layer 2b including the center of each area 3a to 3h located outside the rotation axis 9 of the master plate. The

The method according to the invention has the following steps, which are:
a) During exposure of the recording layer 2 b to the modulated radiation beam 10, the master plate 2 is fixed eccentrically with respect to the axis of rotation 8 of the support structure 1. The rotating shaft 8 of the support structure 1 is substantially perpendicular to the surface of the recording layer 2 b of the master plate 2. The support structure 1 with the fixed master plate 2 rotates along the rotation axis 8.

  b) The first area 3a of the series of areas 3a to 3h is exposed to the radiation beam 10 forming the information track while the center of the first area 3a coincides with the axis of rotation 8 of the support structure 1.

  c) The master plate 2 is ejected from the support structure 1 rotating at 45 degrees around the rotation axis 9 of the master plate 2 with respect to the support structure 1 until the center of the subsequent area 3b coincides with the rotation axis 8 of the support structure 1 . The rotation axis 9 of the master plate exists at a fixed position on the support structure 1. Next, the master plate 2 is fixed to the support structure 1 again.

  d) The following area 3b is exposed to the radiation beam 10 forming the information track, while the center of the following area 3b coincides with the axis of rotation 8 of the support structure 1.

  e) Steps c) and d) are repeated until all 8 areas of the series of areas 3a to 3h are exposed to the radiation beam 10.

  In FIG. 1, it should be noted that all the areas 3a to 3h are exposed and the center of the last exposed area 3h coincides with the axis of rotation 8 of the support structure 1.

  The master plate 2 is circular, has a diameter of 160 mm, and the diameter of the area 3 with spiral or concentric information tracks is 30 mm. The rotation axis 9 of the master plate 2 on the support structure 1 has a distance of 43 mm to the rotation axis 8 of the support structure 1.

  Subsequently, the surface of the recording layer 2b sensitive to the radiation beam of the master plate 2 is conductive, preferably nickel, of about 50 to 100 nm, for example by well-known deposition techniques such as sputtering or wet electroless nickel deposition. Provided with a metal layer. Once metalized, the master plate 2 is easy to use in the electroforming process of nickel stamper generation. Information tracks having data pits in areas 3a to 3h of the master plate 2 are accurately replicated in the electroforming process so that nickel ions gradually deposit on the conductive surface of the master plate 2. The process of forming the stamper on the master plate 2 is a well-known technique. With this technique, this process takes approximately one hour. After the desired stamper thickness is achieved (determined by current / time / deposition rate calculation according to Faraday's law), the master plate 2 and stamper are moved from the electroformed galvanic cell. Subsequently, the nickel stamper is separated from the surface of the master plate 2. The nickel stamper is a negative copy of the master plate 2. Possible residues of the recording layer 2b on the stamper surface are removed by known cleaning techniques. If the metal layer is not nickel, it is preferably removed by dissolving the metal layer with a selective etchant. Thus, the resulting stamper is also known as a father stamper. This father stamper may be used directly in an injection molding apparatus for molding a plastic substrate that again has a positive copy of the information track. Alternatively, the surface of a father stamper called mother stamper, which is used instead to generate a so-called son stamper, which is repeated in the electroforming process and finally placed in an injection molding machine It is possible to regenerate a negative copy. In this manner, multiple sun stampers may be obtained from a single father stamper, resulting in the production of additional optical storage media substrates than would be possible with a single father stamper alone. Furthermore, it offers the possibility to create a backup sun stamper in the event of a missing or damaged sun stamper.

  1 and 2, the support structure 1 has a counterweight to balance the mass of the added master plate 2, so that the center of gravity of the assembly of the support structure 1 and the added master plate 2 is It substantially coincides with the rotational axis 8 of the structure 1.

  The counterweight 5 is movable with respect to the rotating shaft 8 of the support structure 1. In this embodiment, the counterweight 5 can be further detached from the support structure 1 by unscrewing the counterweight from the sled 4, for example.

  The support structure 1 has a centering unit 6 for receiving the master plate 2. Furthermore, the support structure 1 has a chuck 7 that is used to center the support structure on the master recorder.

  It should be noted that the embodiments described above illustrate the invention rather than limit the invention, and that those skilled in the art will be able to design numerous alternative embodiments without departing from the scope of the claims. Should. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word “comprising” or “including” does not exclude the presence of elements or steps other than those listed in a claim. The singular representation of an element does not exclude the presence of a plurality of such elements. The mere fact that certain measures are elaborated in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

  According to the present invention, a method for manufacturing a stamper for use in measuring optical data storage media is provided. A conventional master plate is provided with a series of areas with spiral or concentric information tracks having a relief structure with the center of each area located outside the axis of rotation of the master plate. This is accomplished by using a conventional master recorder and a separate master plate support structure that eliminates the need for complex movement of the master recorder write head.

FIG. 2 is a top view schematically illustrating an embodiment of a support structure and master plate assembly for carrying out the method according to the invention. 2 is a cross-sectional view of the embodiment of FIG. 1 taken along II-II of FIG.

Claims (10)

A stamper manufacturing method for use in the manufacture of an optical data storage medium, wherein the master plate comprises a substrate having a rotating shaft and a recording layer sensitive to a radiation beam provided on the substrate. Are exposed to a modulated radiation beam, and in the method, a series of areas comprising a spiral or concentric information track having a relief structure is provided for each area located outside the rotation axis of the master plate. Formed of the recording layer with a center and subsequently the stamper, and further, in the method, the relief structure of the information track of the master plate is copied, formed on the master plate, and the master Separated from the plate,
a) in the step of exposing the recording layer to a modulated radiation beam, the master plate is eccentrically fixed with respect to a rotation axis of a support structure, the rotation axis of the support structure being the surface of the substrate of the master plate The support structure comprising an added master plate is rotated along the axis of rotation of the support structure;
b) the first area of the series of areas is exposed to a radiation beam forming an information track, while the center of the first area coincides with the axis of rotation of the support structure;
c) The master plate is ejected from the support structure and moved relative to the support structure until the center of a later area coincides with the axis of rotation of the support structure and is fixed again with respect to the support structure. And
d) the latter area is exposed to the radiation beam forming an information track;
e) Steps c) and d) are repeated until all areas of the series of areas are exposed to the radiation beam,
The stamper manufacturing method characterized by the above-mentioned.   In the step c), the master plate rotates around the rotation axis of the master plate, and the rotation axis of the master plate exists at a fixed position on the support structure. 2. A method for producing a stamper according to 1.   3. The method of manufacturing a stamper according to claim 2, wherein the master plate is substantially equal to 360 / n degrees, rotates n−1, and n is an integer larger than 1. 4.   4. The master plate according to claim 2, wherein the master plate has a diameter in the range of 150 to 170 mm, and the diameter of the area with a spiral or concentric information track is shorter than 40 mm. A method for producing a stamper according to claim 1.   5. The n is one of 8, 9, and 10, and the rotation axis of the master plate on the support structure has a distance of 30 to 55 mm to the rotation axis of the support structure. A method for producing a stamper according to claim 1.   Use of the master plate provided with an area of an information track according to the method of claim 1 for the manufacture of a stamper having a negative replicated surface of the master plate.   The support structure has at least one counterweight to balance the mass of the added master plate, and the center of gravity of the support structure and the added master plate assembly substantially coincides with the axis of rotation of the support structure. A support structure suitable for use in the method according to claim 1.   The support structure according to claim 7, wherein the counterweight is movable with respect to the rotation axis of the support structure.   The support structure according to claim 7, wherein the counterweight is removable from the support structure.   Use of a stamper manufactured according to any one of claims 1 to 5 for the manufacture of an optical data storage medium having a diameter shorter than 40 mm.

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